Datalogging with MPPT 100/20 Controller

Been thinking about this a fair bit lately since I've been trying to get better visibility on my motorhome setup (Victron MPPT 100/20 running into a pair of Fogstar 100Ah lithiums).

The question I keep coming back to is — what's the best way to log data from the 100/20 over time? I know Victron have the VE.Direct interface, and I've got the VictronConnect app doing its thing, but that's only really giving me a live snapshot rather than proper historical data I can actually analyse.

A few things I'm specifically wondering about:

• Has anyone used a Raspberry Pi with VE.Direct to USB cable to pull data into something like InfluxDB/Grafana? Seems popular but looks a bit involved for someone who's not massively technical
• Is the GlobalLink 520 worth it for remote monitoring, or is it overkill if the van is just parked on the drive most of the time?
• Anyone managed decent datalogging without a Cerbo GX? The Cerbo feels like a big spend just to get graphs

My main use case is emergency backup at home as well as the motorhome, so I'd love to properly understand my charge/discharge patterns across different seasons — especially heading into winter when I'm relying on it more.

Would be brilliant to hear from anyone who's got a working logging setup, even a basic one. What kit did you end up going with, and was it straightforward to configure? Happy to share what I learn if I get something working properly.

Hey @ExTrucker73, great setup with the Fogstars! The 100/20 connects via VE.Direct, so your easiest route is a Victron Cerbo GX if budget allows — gives you proper datalogging plus remote access through VRM portal. That said, if you want something cheaper, a Raspberry Pi with VE.Direct USB cable running Venus OS is brilliant and costs a fraction. You'd still get full VRM access.

Worth knowing VRM stores 15-minute interval data for free indefinitely, which is genuinely useful for spotting patterns across seasons. I've been running something similar on my narrowboat for about 18 months and the historical graphs have been invaluable for sizing decisions.

What's your main priority — remote monitoring while away, or just local logging when you're on site? That'd help narrow down the best approach for your situation. 🙂

@ExTrucker73 welcome to the forum — brilliant first post, straight to the point with all the relevant details. We love that here!

To add to what @EllaDavies said — if you want proper long-term datalogging rather than just live monitoring, look at pairing VE.Direct with a Raspberry Pi running Venus OS. Turns it into a full GX device on the cheap. I ran this exact combo in my van conversion for about 18 months before upgrading to a proper Cerbo GX, and the historical data it captures is genuinely useful for spotting patterns across seasons.

The Fogstar/MPPT 100/20 combo will produce some really interesting charge curves worth logging — lithium profiles are noticeably different from lead-acid and you'll learn a lot from watching them over time.

If you're feeling fancy, lob a Raspberry Pi on the VE.Direct port and run VictronConnect data into InfluxDB/Grafana — suddenly you've got graphs prettier than anything your Fogstars deserve 📈

@ExBrickie94 ran almost exactly this setup on my static van — Pi Zero W with VE.Direct USB cable into Node-RED pushing to a local InfluxDB/Grafana stack. Works a treat but fair warning: getting the VE.Direct protocol parsed correctly is a faff if you're not comfortable with serial comms. There's a Python library called vedirect that takes most of the pain out of it.

One thing nobody's mentioned yet — if you want historical data without any faffing around at all, the Victron GX Touch or even a cheap Cerbo GX logs everything natively and has a decent web interface. Costs more than a Pi but it just works out of the box. Given you're running Fogstar lithiums, having proper SOC monitoring logged over time is actually worth the extra spend.

@ExBrickie94 @BayTim the Grafana rabbit hole is real — I told myself "just a quick dashboard" and three weekends later I was graphing cloud cover against State of Charge like some kind of solar meteorologist.

Worth noting that Victron's own VRM Portal gets you surprisingly decent datalogging with zero Pi faff — just plug a VE.Direct to USB into a cheap GX device or even a Cerbo GX if you fancy splashing out, and it uploads automatically via your phone's hotspot or a SIM dongle.

For a motorhome that moves around like mine, not having to babysit a Pi when you're bouncing down a B-road is genuinely underrated.